1. Field of the Invention
The present invention relates to an image reproduction device for document processing. The device includes an input unit that provides sheets, a document conveying system that conveys the sheets from the input unit to an output unit to receive processed documents, a sheet processing system that applies an image pattern to a sheet while the sheet is being conveyed from the input unit to the output unit at a processing speed, and a control unit arranged to process the sheets at a nominal processing speed, at a nominal sheet distance and a nominal document quality, the image reproduction device is arranged to operate at the nominal processing speed continuously, and to process the sheets at a second processing speed, the second processing speed being different from the nominal processing speed while the sheets are processed at the nominal sheet distance and the nominal document quality.
The invention further relates to a method of controlling the image reproduction device for document processing. The method includes the steps of processing the sheets at a nominal processing speed, at a nominal sheet distance and a nominal document quality, the image reproduction device being arranged for operating at the nominal processing speed continuously, and processing the sheets at a second processing speed, the second processing speed being higher than the nominal processing speed while the sheets are processed at the nominal sheet distance and the nominal document quality.
2. Description of Background Art
An apparatus for copying documents and method of controlling document processing is known from U.S. Pat. No. 4,319,874. The apparatus includes a fuser for fixing toner images to copy substrates by passing the substrates between two pressure engaged fuser members, one of which is heated. A control for effecting movement of the members at two different speeds is provided such that the members are moved at the higher speed when a small number of copies are made and then at the lower speed when a large number of copies are being made. The control includes a temperature sensor for sensing the temperature of the heated member, which is used to generate a signal when the temperature of the member falls to a predetermined value, the signal being employed for changing the speed of the members from the higher speed to the lower speed.
In the known system, when the temperature sensor indicates the predetermined temperature has been reached, the speed is switched to a nominal operating speed at which the apparatus can be operated continuously for making a large number of copies. However, no further control of the internal operation of the apparatus is provided. Moreover, an instant switch to another processing speed can not be done while sheets are travelling through the system or the sheets will be torn or wrinkled due to the accelerations or decelerations taking place. Consequently, a speed change can only be done after emptying the sheet trajectories, whereafter the process can be restarted at the changed processing speed, which costs time and decreases productivity.